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<FONT color="green">001</FONT>    package gates;<a name="line.1"></a>
<FONT color="green">002</FONT>    <a name="line.2"></a>
<FONT color="green">003</FONT>    import register.Register;<a name="line.3"></a>
<FONT color="green">004</FONT>    import gates.FunctionGate;<a name="line.4"></a>
<FONT color="green">005</FONT>    import mathtools.Complex;<a name="line.5"></a>
<FONT color="green">006</FONT>    /**<a name="line.6"></a>
<FONT color="green">007</FONT>     * Functional representation of a NOT gate.<a name="line.7"></a>
<FONT color="green">008</FONT>     * Generally it is the X Pauli matrix<a name="line.8"></a>
<FONT color="green">009</FONT>     * This implements Gate interface, so consult this for public methods.<a name="line.9"></a>
<FONT color="green">010</FONT>     * The constructor for this gate is protected, so generating such an object is left<a name="line.10"></a>
<FONT color="green">011</FONT>     * for the factory class &lt;code&gt;Factory&lt;/code&gt;<a name="line.11"></a>
<FONT color="green">012</FONT>     * @author Jan Zaucha<a name="line.12"></a>
<FONT color="green">013</FONT>     *<a name="line.13"></a>
<FONT color="green">014</FONT>     */<a name="line.14"></a>
<FONT color="green">015</FONT>    public class NotFunction extends FunctionGate {<a name="line.15"></a>
<FONT color="green">016</FONT>    <a name="line.16"></a>
<FONT color="green">017</FONT>            /** Store the target qubit the gate acts on*/   <a name="line.17"></a>
<FONT color="green">018</FONT>            private int target;<a name="line.18"></a>
<FONT color="green">019</FONT>            <a name="line.19"></a>
<FONT color="green">020</FONT>    <a name="line.20"></a>
<FONT color="green">021</FONT>    <a name="line.21"></a>
<FONT color="green">022</FONT>            /**<a name="line.22"></a>
<FONT color="green">023</FONT>             * Protected constructor for a functional representation of a NOT gate<a name="line.23"></a>
<FONT color="green">024</FONT>             * Requires a target bit for the gate to operate on, however if the target bit is<a name="line.24"></a>
<FONT color="green">025</FONT>             * -1 the gate will NOT all qubits<a name="line.25"></a>
<FONT color="green">026</FONT>             * @param target the target bit for phase shift (counting qubits from 0)<a name="line.26"></a>
<FONT color="green">027</FONT>             */<a name="line.27"></a>
<FONT color="green">028</FONT>            protected NotFunction(int target){<a name="line.28"></a>
<FONT color="green">029</FONT>                    this.target = target+1; // since first qubit is given by 0, add one so first qubit is 1, 2nd is 2 etc...<a name="line.29"></a>
<FONT color="green">030</FONT>                                            //we then NOT all if target is 0.. <a name="line.30"></a>
<FONT color="green">031</FONT>                    <a name="line.31"></a>
<FONT color="green">032</FONT>            }<a name="line.32"></a>
<FONT color="green">033</FONT>    <a name="line.33"></a>
<FONT color="green">034</FONT>            /**<a name="line.34"></a>
<FONT color="green">035</FONT>             * Returns the name of the gate regardless of representation.<a name="line.35"></a>
<FONT color="green">036</FONT>             */<a name="line.36"></a>
<FONT color="green">037</FONT>            public String getName() {<a name="line.37"></a>
<FONT color="green">038</FONT>                    return "Not";<a name="line.38"></a>
<FONT color="green">039</FONT>            }<a name="line.39"></a>
<FONT color="green">040</FONT>    <a name="line.40"></a>
<FONT color="green">041</FONT>            /**<a name="line.41"></a>
<FONT color="green">042</FONT>             * Applies this gate to the given register. See interface &lt;code&gt;Gate&lt;/code&gt; for usage.<a name="line.42"></a>
<FONT color="green">043</FONT>             * @param r the register <a name="line.43"></a>
<FONT color="green">044</FONT>             */<a name="line.44"></a>
<FONT color="green">045</FONT>            public void apply(Register r) {<a name="line.45"></a>
<FONT color="green">046</FONT>                    if (target &gt; r.getNumQbits() || target &lt; 0){<a name="line.46"></a>
<FONT color="green">047</FONT>                            throw new IllegalArgumentException("Target qubit not in register. Register size (qubits): " + r.getNumQbits() + " Target qubit: " + target);<a name="line.47"></a>
<FONT color="green">048</FONT>                    }<a name="line.48"></a>
<FONT color="green">049</FONT>    <a name="line.49"></a>
<FONT color="green">050</FONT>                    // if target is flagged "-1" we phase shift all qubits<a name="line.50"></a>
<FONT color="green">051</FONT>                    if(target==0){<a name="line.51"></a>
<FONT color="green">052</FONT>                            for(int i = 1; i&lt;r.getNumQbits()+1; i++){<a name="line.52"></a>
<FONT color="green">053</FONT>                                    this.applyToSingleQubit(i, r);<a name="line.53"></a>
<FONT color="green">054</FONT>                            }<a name="line.54"></a>
<FONT color="green">055</FONT>                            <a name="line.55"></a>
<FONT color="green">056</FONT>            <a name="line.56"></a>
<FONT color="green">057</FONT>                    }<a name="line.57"></a>
<FONT color="green">058</FONT>                    // else apply to a given single qubit<a name="line.58"></a>
<FONT color="green">059</FONT>                    else{<a name="line.59"></a>
<FONT color="green">060</FONT>                            this.applyToSingleQubit(target, r);<a name="line.60"></a>
<FONT color="green">061</FONT>                    }<a name="line.61"></a>
<FONT color="green">062</FONT>            }<a name="line.62"></a>
<FONT color="green">063</FONT>            <a name="line.63"></a>
<FONT color="green">064</FONT>            /**<a name="line.64"></a>
<FONT color="green">065</FONT>             * Private method that applies NOT gate to the given register given the target qubit. <a name="line.65"></a>
<FONT color="green">066</FONT>             * @param targetVar target qubit for the phase shift !(count qubits from 1 to N)!<a name="line.66"></a>
<FONT color="green">067</FONT>             * @param r the register <a name="line.67"></a>
<FONT color="green">068</FONT>             */<a name="line.68"></a>
<FONT color="green">069</FONT>            private void applyToSingleQubit(int targetVar, Register r){<a name="line.69"></a>
<FONT color="green">070</FONT>                    int numStates = r.getHeight();    // number of states in register<a name="line.70"></a>
<FONT color="green">071</FONT>                    // create array to store updated register<a name="line.71"></a>
<FONT color="green">072</FONT>                    Complex [] newRegister = new Complex [numStates]; <a name="line.72"></a>
<FONT color="green">073</FONT>                    // interval size- # of amplitudes in one interval of "function"<a name="line.73"></a>
<FONT color="green">074</FONT>                    int intervalSize = (int)(numStates/Math.pow(2,targetVar));<a name="line.74"></a>
<FONT color="green">075</FONT>                    // first j loop for number of intervals <a name="line.75"></a>
<FONT color="green">076</FONT>                    for(int j=0; j&lt; Math.pow(2, targetVar -1); j++){<a name="line.76"></a>
<FONT color="green">077</FONT>                            // nested loop: flip states <a name="line.77"></a>
<FONT color="green">078</FONT>                            for(int i=1; i &lt;intervalSize +1; i++){<a name="line.78"></a>
<FONT color="green">079</FONT>                                    newRegister[2*j*intervalSize +i-1] = r.getElement(0, (2*j+1)*intervalSize +i-1);<a name="line.79"></a>
<FONT color="green">080</FONT>                                    newRegister[(1+2*j)*intervalSize +i-1] = r.getElement(0, (2*j)*intervalSize +i-1);<a name="line.80"></a>
<FONT color="green">081</FONT>                            }<a name="line.81"></a>
<FONT color="green">082</FONT>    <a name="line.82"></a>
<FONT color="green">083</FONT>                    }<a name="line.83"></a>
<FONT color="green">084</FONT>                    // Now update our real qubits <a name="line.84"></a>
<FONT color="green">085</FONT>                    r.update(newRegister);<a name="line.85"></a>
<FONT color="green">086</FONT>                    // normalize register<a name="line.86"></a>
<FONT color="green">087</FONT>                    r.normalise();<a name="line.87"></a>
<FONT color="green">088</FONT>    <a name="line.88"></a>
<FONT color="green">089</FONT>            }<a name="line.89"></a>
<FONT color="green">090</FONT>    <a name="line.90"></a>
<FONT color="green">091</FONT>    <a name="line.91"></a>
<FONT color="green">092</FONT>    <a name="line.92"></a>
<FONT color="green">093</FONT>    }<a name="line.93"></a>




























































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